1. Field of the Invention
The present invention relates to an electronic apparatus such a as mobile cell phone.
2. Description of the Related Art
An example of a portable electronic apparatus, such as a mobile phone, includes a housing and a first circuit board (hereinafter also referred to as a “main circuit board”) in the housing. Electronic components are mounted on the first circuit board. To block noise and the like from the electronic components mounted on the main circuit board, a shield casing is attached to the main circuit board.
Another example of a portable electronic apparatus includes a second circuit board (hereinafter also referred to as a “key substrate”) and a key unit in addition to the first circuit board. Key switches and light emitting diode (LED) units for illumination are mounted on the key substrate and the key unit is capable of pressing the key switches. In the portable electronic apparatus having such a structure, the key substrate is generally stacked on an upper surface (surface at the side opposite to the main circuit board) of the shield casing.
The portable electronic apparatus, in particular, the mobile phone has been demanded to reduce the size, in particular, the thickness thereof. To comply with such a demand, it is necessary to provide a housing and a shield casing capable of ensuring the strength (in particular the rigidity) of the entire body of the apparatus. Accordingly, high-rigidity material, such as metal, is used as the main material of the shield casing.
Recently, portable electronic apparatuses have been formed so as to have the following structure. That is, the main circuit board is formed such that the length thereof is about one-half of the entire length of the shield casing. The main circuit board is disposed at a section of the shield casing corresponding to about one half of the shield casing near one end thereof, and a battery is disposed in a section corresponding to the remaining half of the shield casing which is free from the main circuit board. Accordingly, the main circuit board and the battery are arranged in the longitudinal direction of the shield casing without overlapping each other in a plan view of the main circuit board (when the main circuit board is viewed in the thickness direction).
In the above-described structure, no rigid body is disposed at the boundary between the main circuit board and the battery, and therefore the strength at the boundary is weaker than the strengths at other regions. This effect is particularly significant in a thin portable electronic apparatus in which the shield casing and the housing are relatively weak. Therefore, it is necessary to increase the rigidity.